//创建一个库
CREATE DATABASE zy1
use zy1
// 创建一个班级表(classes)，包含字段id,name
CREATE TABLE classs(
id INT PRIMARY KEY auto_increment,
cname VARCHAR(20)
)
//创建一个学生表(students),包含字段id,name,birthday,gender,score,class_id
CREATE TABLE students(
id INT PRIMARY KEY auto_increment,
sname VARCHAR(10),
birthday date,
gender VARCHAR(20),
score INT,
class_id INT
)
//在班级表中添加三条记录 id:1 name:一年级，id:2 name:二年级，id:3 name:三年级
INSERT into classs(cname)
VALUES("一年级"),
("二年级"),
("三年级")
//4 在员工表里添加六条记录，
INSERT into students(sname,birthday,gender,score,class_id)
VALUES('张三','2010-11-10','男','100','1'),
('李四','2012-11-10','女','75','1'),
('王五','2014-11-10','男','80','2'),
('小明','2013-11-10','女','60','2'),
('小李','2015-11-10','女','30','3'),
('小刘','2008-11-10','男','90','3')
//5 使用pymysql模块来查询每个班级的平均分
select AVG(s.score),c.cname
FROM students s ,class c
WHERE s.class_id=c.id
GROUP BY s.class_id
//修改张三的名字为张五
UPDATE students SET sname="张五" WHERE sname="张三"
//删除班级名字为”三年级”的所有学生
delete FROM students WHERE class_id="3"
//查询一年级分数最高的人
SELECT s.sname,MAX(s.score) as "最高成绩"
FROM students s
WHERE s.class_id=1
//查询所有学生的年级信息（用子查询实现）
select c.cname,s.sname
from class c,students s
WHERE s.class_id=c.id
//查询以‘小’开头的名字为一个字学生
SELECT * FROM students where sname like '小_'
//查询出生日期在2008-11-10到2012-11-10的学生
SELECT s.sname,s.birthday
from students s
where s.birthday>'2008-11-10' and s.birthday<'2012-11-10'
//创建一个分类表(cate)，包含字段id,name
CREATE TABLE cate(
id INT PRIMARY KEY auto_increment,
cname VARCHAR(20)
)
//创建一个库
CREATE DATABASE zy2
use zy2
//创建一个商品表(goods),包含字段id,name,number,create_time,price,cate_id
CREATE TABLE goods(
id INT PRIMARY KEY auto_increment,
gname VARCHAR(10),
number INT,
create_time date,
price DOUBLE,
cate_id INT
)
//在分类表中添加三条记录 id:1 name:服装，id:2 name:玩具，id:3 name:家电
INSERT into cate(cname)
VALUES("服装"),
("玩具"),
("家电")
//在商品表里添加六条记录
INSERT into goods(gname,create_time,number,price,cate_id)
VALUES('羽绒服','2010-11-10','10','1.00','1'),
('轻便服','2012-11-10','30','2.00','1'),
('汽车','2014-11-10','40','2.00','2'),
('公主','2013-11-10','50','6.00','2'),
('橡皮泥','2015-11-10','23','3.50','2'),
('电饭煲','2008-11-10','3','3.00','3')
//使用pymysql模块来查询所有的分类及商品
select * from goods g LEFT JOIN cate c ON g.cate_id=c.id
//把名字为‘羽绒服’修改成‘棉衣’
UPDATE goods SET gname="棉衣" WHERE gname="羽绒服"
//删除名字为‘电饭煲’的记录
delete FROM goods WHERE gname="电饭煲"
//查询‘服装’分类下面库存最多的商品信息
SELECT g.gname,MAX(g.number) as "库存最多"
FROM goods g,cate c
WHERE c.cname="服装"
//查询分类下有商品分类信息
select c.cname,g.gname
from cate c,goods g
WHERE c.id=g.cate_id
//查询以‘服’结束的商品信息
SELECT * FROM goods where gname like '%服'
//查询创建日期在2008-11-10到2012-11-10的之间的商品
SELECT g.gname,g.create_time
from goods g
where g.create_time>'2008-11-10' and g.create_time<'2012-11-10'
//创建一个数据库 cart
CREATE DATABASE cart;
//使用新创建的数据库,在数据库下建立两张表
//用户表(users): id 姓名 身高
//购物车表(user_cart):id 商品名称 购买数量 总价 是否删除 用户id
//创建一个分类表(cate)，包含字段id,name
CREATE TABLE users(
id INT PRIMARY KEY auto_increment,
uname VARCHAR(20),
height DOUBLE
)
CREATE TABLE user_cart(
id INT PRIMARY KEY auto_increment,
cname VARCHAR(20),
number INT,
price DOUBLE,
deleteu int,
uid INT
)
INSERT into users(uname,height)
VALUES("张三","1.80"),
("李四","1.75"),
("小明","1.34")
//在购物车表中加入以下记录（1代表未删除，0代表删除）
INSERT into user_cart(cname,number,price,deleteu,uid)
VALUES("商品一",10,100,1,1),
("商品二",3,89,0,1),
("商品三",2,30,1,1),
("商品四",10,50,1,2),
("商品五",3,10,1,2),
("商品六",1,76,1,2)
//7.更新李四的购物车中 商品五的名字为商品5
UPDATE user_cart SET cname="商品5" WHERE cname="商品五"
//8.查询身高大于1米并且购物车没删除的用户和购物车信息
select * from users u right JOIN user_cart c ON c.uid=u.id WHERE u.height>1 AND c.deleteu=1
//9.查询购物车中删除和没删除的总价和为多少
SELECT sum(price) FROM user_cart
//10.查询每个用户没删除的购物车的数量大于1的记录，并按降序排列，取三条记录
SELECT * FROM user_cart c
WHERE c.deleteu=1 AND number>1
ORDER BY number DESC LIMIT 0,3
//11.按是否删除分组，查询平均总价格大于10的用户和购物车信息
SELECT * FROM user_cart c
GROUP BY deleteu
HAVING sum(c.price)/count(*)>10
//12.查询有购物车的用户和购物车信息
select * from users u right JOIN user_cart c ON c.uid=u.id WHERE c.deleteu=1
//13.删除张三购物车中已删除的购物车信息
delete FROM user_cart c, users u WHERE c.deleteu=0 AND u.uname="张三"
1.创建test数据库
create database test (A)
use test
2.在test数据库中创建student表id设置为主键自增长
create table student(
id int primary key auto_increment,
name varchar(20),
score int,
address varchar(50),
usermail varchar(20)
)
3.向student表中添加记录
insert into student(id,name,score,address,usermail)
values(1,'张三',98,'北京','[email protected]'),
(2,'李四',88,'上海','[email protected]'),
(3,'王五',78,'广州','[email protected]'),
(4,'赵六',68,'深圳','[email protected]'),
(5,'孙七',58,'杭州','[email protected]'),
(6,'小红',48,'北京','[email protected]'),
(7,'小黑',99,'上海','[email protected]'),
(8,'小绿',100,'杭州','[email protected]'),
(9,'小粉',60,'杭州','[email protected]'),
(10,'小紫',70,'黑龙江','[email protected]')
4.使用sql语句查询出表中的所有内容
select * from student
5.使用sql语句查询出表中所有同学的id,name,score
select id,name,score from student
6.更改useremail字段的数据类型为varchar(50)
alter table student modify usermail varchar(50)
7.向表中添加一个字段，字段名称为“pingjia”,字段类型为varchar(20)
alter table student add pingjia varchar(20)
8.更改姓名是张三的同学的分数为88
update student set score='88' where name=‘张三’
9.如果80分为及格线，查询出所有及格的同学的详细信息
select * from student where score>=80
10.把姓名是“小红”的同学的分数在原来的基础上+40
update student set score=score+40 where name='小红'
11.使用关键字in,查询id值是1或5或7的同学的基本信息
select * from student where id in(1,5,7)
12.查询id值在5至8的所有同学的基本信息
select * from student id where id>=5 and id<=8
13.查询姓名是小红并且分数大于60的同学的基本信息
select * from student where name='小红' and score>60
14.查询姓名是小红或者分数大于90的同学的基本信息
select * from student where name='小红' or score>90
15.查询score字段值是NULL的同学的基本信息
select * from student where score='null'
16.查询score字段值不是NULL的同学的id和name
select id,name from student where score is not null
----------------------------------------------------------------------------------------------
1创建一个学校数据库（jiyun） (B)
create database jiyun
2创建课程（lesson）id（整形主键）name（课程名称）
create table lesson(
id int primary key auto_increment,
name varchar(50)
)
3创建一个班级(cls)，包含字段id（整形主键）name(班级名称)number(班级人数)lesson_id（课程名称id）
CREATE TABLE cls (
id int primary key auto_increment,
name varchar(50),
number varchar(50),
lesson_id varchar(50)
)
4在lesson表中插入两数据
insert into lesson(name)VALUES
('python高级'),
('数据库vue')
5在班级表中插入6条记录
insert into cls(name,number,lesson_id)values
('1905A','22','1'),
('1906A','44','1'),
('1904A','33','1'),
('1901A','18','2'),
('1902A','48','2'),
('1903A','56','2')
6.查询类型为 'python高级' 的所有班级、人员数量
select * from cls where lesson_id in(select id from lesson where name='python高级')
7.查询每个班级中 人数最多、最少
select max(number) as '人数最多',min(number) as'人数最少' from cls
8.查询所有人员数量大于平均人数的班级，并且按班级人数降序排序
select * from cls where number < (select avg(number) from cls) order by number desc
9.修改cls表中'1902A'班级数量为44
update cls set number='44' where name='1902A'
----------------------------------------------------------------------------------------
1.创建数据库 (C)
create database db_test
use db_test
2.在test数据库中创建yuangong表
create table yuangong(
sid int primary key auto_increment,
sname varchar(20) not null,
sex varchar(4) deeault '男',
job varchar(20)not null,
birthday date,
salary decimal,
comm decimal,
widthhold int
)
4.表中添加如下记录
insert into yuangong (sid,sname,sex,job,birthday,salary,comm,widthhold)values
(1001,'张三','男','高级程师','1975-1-1',2200,1100,200),
(1002,'李四','女','助工','1985-1-1',1200,200,100),
(1003,'王五','男','工程师','1978-11-11',1900,700,200),
(1004,'赵六','男','工程师','1979-1-1',1960,700,150)
4.修改表名为emp
alter table yuangong RENAME emp
5.向表中添加字段Hobby,设置类型为varchar(50),设置唯一约束
alter table emp add hobby varchar(50) unique
6.使用desc语句查看表结构
show create table emp
7.向表中添加记录，字段对应值分别为（1005，林青霞，女，架构师，1969-12-12，8000，NULL，100，阅读）
insert into emp values(1005,'林青霞','女','架构师','1969-12-12',8000,null,100,'阅读')
8.修改sname字段的类型为varchar(20)
alter table emp modify sname VARCHAR(20)
9.查询表中sid字段的值从是1002或1003或1005员工的所有记录
select * from emp where sid = 1002 OR sid = 1003 OR sid = 1005
10.修改表中job值是高级工程师员工的job为“架构师”
update emp set job='架构师' where job='高级程师'
11.删除表中sid是1003并且job是王五的员工的记录
delete from emp where sid = 1003 and job = '王五'
12.修改表中姓名是1004员工的salary在原来的基础上-300
update emp set salary = salary - 300 where sid = 1004
----------------------------------------------------------------------------------------------
1.创建库 (D)
create database databook
2.自定义类Book，表名为book
use databook
create table book(
id int primary key auto_increment,
bookname varchar(10),
price int,
author varchar(20),
publish varchar(20)
)
2.向表里添加10条数据
insert into book(bookname,price,author,publish) values
('北平无故事',25,'刘和平','作家出版社'),
('人间失格',16,'太宰治著','作家出版社'),
('高兴',14,'贾平凹','人民出版社'),
('源氏物语',57,'刘和平','人民出版社'),
('卡夫卡文集',9,'卡夫卡','邮电出版社'),
('大家',12,'王蒙','邮电出版社'),
('拉片子',37,'杨健','清华出版社'),
('古代散文',5,'归有光','安徽出版社'),
('百花散文',6,'孙虹选','百花文艺出版社'),
('方令孺散文集',5,'方令孺','安徽文艺')
3.查询所有图书的信息，并按价格降序显示
select * from book where price order by price asc
4.查询所有作家出版社的图书信息，并按价格降序显示
select author from book where price order by price desc
5.查询出所有刘和平的图书信息 ，并输出
select * from book where author = '刘和平'
6.删除ID是2的记录，如果没有相关记录则提示
delete from book where id = 2 select * from book
7.将所有价格不足10元的图书调到10元，并查看信息
update book set price = 10 where price <10
8.查看所有图书的价格情况，并升序显示
select price from book where price order by price asc
9.查看所有价格低于20元的图收信息
select publish from book where price <=20
10.所有图书的价格上调20%，并查看信息
select * from book
update book set price = price*1.2